#include<bits/stdc++.h>

using namespace std;

int main(){
	int m, t, s;
	cin >> m >> t >> s;
	if(t != 0){
		if(s % t == 0){
			m -= s / t;
			if(m <= 0){
			m == 0;
		}
		}else{
			m -= s / t + 1;
			if(m <= 0){
			m == 0;
		}
		}
		if(m <= 0){
			m == 0;
		}
	}else{
		m == 0;
	}
	cout << m;
	return 0;
  }